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宇宙工学・惑星科学・宇宙物理の最新プレプリント。

astro-ph.HEastro-ph.GAgr-qc

Probing an Intermediate-Mass Black Hole Companion of Sagittarius A* with Pulsar Timing

Zexin Hu, Lijing Shao

An intermediate-mass black hole (IMBH) hidden in our Galactic Center (GC) may explain the puzzling observations of the stellar distribution around Sagittarius A* (Sgr A*), the supermassive black hole (SMBH) in the GC. Future observations with the next-generation radio telescopes, such as the SKA, are promising to discover pulsars orbiting around Sgr A*, and thus provide the possibility of constraining the hidden IMBH with pulsar timing. We study the detectability of a third-body, the IMBH, in th…

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astro-ph.SRastro-ph.IM

The Payne Zero Project I: Stellar Spectra from Physical Models in Seconds

Yuan-Sen Ting, Elliot M. Kim

Modern stellar surveys measure millions of spectra, yet one self-consistent atmosphere and spectrum can require tens of minutes. This cost has motivated grids, spectral emulators, and data-driven models. We present Payne Zero, which reorganizes one-dimensional LTE Kurucz calculations for GPU-native synthesis and multicore atmosphere iteration, and validate it against the original Fortran programs. A 300--1000 nm solar spectrum sampled at $R_{\rm grid}=300{,}000$ takes about 14 s on an NVIDIA H10…

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cond-mat.mtrl-sciphysics.space-ph

Recrystallisation phenomena in an ultrafine-grained Al-Mg-Si alloy revealed by correlative in situ EBSD and TEM heating

Moritz Theissing, Sandra Gonzaga, Patrick Willenshofer, Thomas M. Kremmer, Stefan Pogatscher, Stefan Mitsche, Frank F. Sene, Matheus A. Tunes et al.

Ultrafine-grained (UFG) aluminium alloys are promising lightweight structural materials for space applications, where a high grain-boundary density can act as sinks for irradiation-induced defects. Their deployment, however, is contingent on thermal stability: aluminium components in low-Earth orbit can reach $\sim$200 $^\circ$C under solar irradiation, close to where severely deformed aluminium alloys recrystallise. Accurate, bulk-representative determination of recrystallisation onset is there…

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astro-ph.GA

Evidence for Azimuthally Anisotropic MgII Absorption around DESI Luminous Red Galaxies

Xuanyi Wu, Cheng Li

We use DESI DR1 luminous red galaxies (LRGs) and background quasar spectra to measure the mean MgII equivalent-width field around massive quiescent galaxies as a function of projected radius and azimuth relative to the projected major axis. Our forced-measurement approach assigns a MgII doublet-window EW to every LRG-quasar pair, including spectra without individually detected absorbers, and subtracts a redshift-matched random-control signal measured from the same normalized quasar spectra. The…

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astro-ph.IMcs.AIcs.RO

HELIOS: An LLM-Driven Autonomous Indirect Trajectory Optimization Agent

An-yi Huang

Low-thrust trajectory optimization is a core technology in deep-space mission design. Indirect methods based on Pontryagin's Minimum Principle (PMP) offer rigorous optimality guarantees, yet their practical application faces three bottlenecks: (1) transversality conditions must be derived case by case for each constraint type; (2) different dynamics models require repeated code rewrites; and (3) shooting equations are highly sensitive to initial guesses. This paper presents HELIOS (Heuristic Eng…

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astro-ph.HE

Shock breakout from mildly relativistic ejecta in a dense wind: the case of EP260321a/SN~2026gzf

Akihiro Suzuki, Keiichi Maeda, Toshikazu Shigeyama

We present shock breakout (SBO) modeling of the recently discovered X-ray transient EP260321a detected by the \textit{Einstein Probe} mission. Our semi-analytic model, based on our previous work, follows the interaction between a supernova ejecta with a mildly relativistic outer envelope and a dense, wind-like circumstellar medium (CSM) by using a thin-shell approximation that incorporates relativistic effects. We find that the observed properties of the X-ray emission are well explained by the…

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astro-ph.EPastro-ph.SR

JWST/NIRCam Imaging of Young Stellar Objects. IV. Detailed Imaging of the Protoplanetary Disk around TW Hya

Yu-Chia Lin, Jarron Leisenring, Schuyler G. Wolff, Justin Hom, Kellen Lawson, Ewan S. Douglas, George Rieke, Gabriele Cugno et al.

As the nearest protoplanetary disk to Earth ($d = 60.14$ pc), TW Hya is one of the most studied protoplanetary disks and a critical benchmark for testing planet formation theories. We present high-contrast coronagraphic imaging of the TW Hya disk from JWST/NIRCam across four filters (F187N, F200W, F356W, and F444W). We detect the disk's scattered-light emission in F200W, F356W, and F444W. An elliptical fit to the disk image yields an average inclination of $i = 8.74^{+1.03}_{-0.94}$ degrees and…

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astro-ph.GA

The effect of triaxial galaxy shapes on the dynamics of triple supermassive black holes in a cosmological context

Navonil Saha, Margarita Sobolenko, Peter Berczik, Andreas Just, Fazeel Mahmood Khan

The hierarchical nature of galaxy formation in the Lambda cold dark matter ($Λ$CDM) cosmological framework model often leads to the presence of multiple supermassive black holes (SMBHs) in the galactic nuclei. The timescale over which galaxies merge plays a crucial role in shaping the dynamical evolution and the merger dynamics of their central SMBHs. While binary SMBH evolution has been extensively studied, the long-term dynamics of triple SMBH systems, especially in realistic, nonspherical gal…

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astro-ph.EP

Predicted Ejecta Dynamics and Observability of the 2026 Falcon 9 Upper Stage Lunar Impact

William Jo, David B. Goldstein, Philip L. Varghese, Laurence M. Trafton, Jordan K. Steckloff, Arnaud Mahieux

On Aug. 5 at 06:34 UTC, a Falcon 9 upper stage (~3,900 kg) will strike the lunar surface at 2.43 km/s, yielding a potentially visible debris plume. We present a study of the expected impact dynamics and resulting possibly observable debris field. The debris plume should reach roughly 15 to 20 km in altitude for the ejecta curtain and 75 to 100 km for the central ejecta spike, extend 183 km laterally from the impact point near the sunlit limb, and yield a peak dust column density above 10 km alti…

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astro-ph.SRastro-ph.GA

A Century of Novae in the Large Magellanic Cloud

Allen W. Shafter

A comprehensive study of novae in the Large Magellanic Cloud (LMC) is presented. A total of 66 nova eruptions have been reported in the LMC over the past century (1926-2025). Of these, a total of 48 eruptions from 39 unique progenitor systems (9 eruptions are recurrences of 4 known recurrent novae) have sufficient photometric data to permit the maximum magnitudes and rates of decline to be reliably estimated. These data confirm earlier studies showing that LMC novae are, on average, slightly mor…

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astro-ph.GAastro-ph.SR

Neighbors, Not Kin: Kinematic evidence for tidal tails from NGC 7492 along the Sagittarius stream

Camila Navarrete, Álvaro Rojas-Arriagada, Andrés E. Piatti, Julio A. Carballo-Bello, Luca Sbordone, Richa Kundu, Vasily Belokurov, Sergey E. Koposov et al.

The formation, extension, and morphology of extra-tidal stars around globular clusters depend on the internal kinematics of the host cluster and the Galactic potential. Tracing the kinematics of faint tidal tails sheds light on their formation and contribution to the Milky Way halo. NGC 7492 is an outer halo globular cluster with conflicting evidence regarding the presence of tidal tails. If present, the tails are expected to be faint and overlap on the sky with the Sagittarius stream, located a…

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astro-ph.IM

Progress of the design of the 12-m optical, Wide-field Spectroscopic Telescope (WST)

P. Dierickx, G. Gausachs, C. Cudennec, D. Lee, R. Bacon, T. Travouillon, O. Bellido-Tirado, B. Sassolas et al.

The Wide-Field Spectroscopic Telescope (WST) is a 12-m class, Alt-Az optical telescope providing two simultaneous foci, 2 degrees and 3 by 3 arc minutes respectively, for Multi-Object Spectroscopy (MOS) and Integral Field Spectroscopy (IFS) at visible wavelengths. Within the framework of the Horizon Programme, the project has been approved for phase A funding by the EC in 2024 and is currently undergoing intensive development. The optical design relies on a corrected Cassegrain solution feeding…

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astro-ph.EP

A uniform transit survey of 461 ExoFOP M-dwarf TOI hosts: Follow-up prioritization and new transit candidates

Yohann Tschudi

Context. M dwarfs are favorable hosts for small transiting planets. A transit-detection and statistical-validation pipeline was previously developed and validated at the photometric noise frontier, on M3-M6 dwarfs observed in few sectors. Aims. That pipeline is applied uniformly to the full active ExoFOP M-dwarf TOI population, 461 hosts (M0-M6) each hosting a confirmed planet (CP) or planet candidate (PC), to test its recovery and classification of the cataloged signals and to prioritize the ca…

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astro-ph.GA

Spatial Correlations of PAH, UV, H$α$ Emission and IMF - PAH Variations in the Star-Forming Complexes of NGC 628

S Amrutha, Dimitra Rigopoulou, Mousumi Das, Jyoti Yadav

We examine the spatial correlation of emission from polycyclic aromatic hydrocarbons (PAH) (3.3 $μ$m, 7.7 $μ$m, and 11.3 $μ$m) with the far-ultraviolet (FUV), near-ultraviolet (NUV), and H$α$ emission from star-forming complexes (SFCs) in different regions of NGC 628. We use the James Webb Space Telescope to detect PAH emission, along with the Ultraviolet Imaging Telescope and Multi Unit Spectroscopic Explorer observations to sample the UV and H$α$ emission, respectively. We investigate the corr…

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astro-ph.SRphysics.plasm-phphysics.space-ph

Spectral properties of mesoscale fluctuations in interplanetary coronal mass ejections

Anna-Sofia Jylhä, Simon Good, Emilia Kilpua

Magnetic fields in interplanetary coronal mass ejections (ICMEs) often display a flux rope structure at large scales and a turbulent cascade of fluctuations at smaller scales. However, the nature of fluctuations at transition scales between the flux rope and turbulence - i.e., at mesoscales - has not been previously examined in detail. Mesoscale fluctuations of the magnetic field in 142 ICME intervals with clear flux rope signatures at 1 au have been examined using wavelet power spectra, with "m…

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astro-ph.EPastro-ph.SR

Angular Momentum of Planet-Forming Disks: Implications for Infall Driven Misalignments

Aashish Gupta, Cristiano Longarini, L. Ilsedore Cleeves, Giovanni P. Rosotti, Edwin A. Bergin, Cathie J. Clarke, Michael Küffmeier, Zhi-Yun Li et al.

Context. A significant fraction (>30%) of planet-forming disks and planetary are misaligned with respect to the rotational axis of their host stars, yet the dominant mechanism responsible for these misalignments remains unclear. Aims. We aim to observationally constrain the angular momentum of Class II protoplanetary disks and assess whether late-stage infall of material can bring sufficient angular momentum to tilt them. Methods. We first computed the angular momenta of 15 disks with surface de…

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astro-ph.HE

Dust Without Na I D Trace: The Case of Highly Attenuated Type Ib SN 2024vjc

Javier Silva-Farfán, Keiichi Maeda, Andrea Pastorello, Hanindyo Kuncarayakti, Takashi Nagao, Giorgio Valerin, Andrea Reguitti, Dino Pierluigi Fugazza et al.

Understanding dust attenuation toward extragalactic transients is critical for recovering their intrinsic properties and probing the local environments of distant galaxies. A popular diagnostic is the Na I D absorption equivalent width widely applied to extragalactic transients. In this paper, we present early-time optical and near-infrared observations of the Type Ib supernova (SN) SN 2024vjc, followed for $\sim$130 days post-explosion. SN~2024vjc exhibits only weak Na~I~D absorption, indicatin…

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gr-qcastro-ph.HEhep-th

Upper bounds on the force function in spatially regular self-gravitating matter configurations

Shahar Hod

We use the non-linearly coupled Einstein-matter field equations to prove four theorems that bound from above the dimensionless force function ${\cal F}=4πr^2\cdot p(r)$ in spatially regular curved spacetimes of spherically symmetric self-gravitating matter configurations [here $p(r)$ is the radially-dependent pressure inside the spatially regular matter configurations]. In particular, for generic (not necessarily isotropic) matter configurations it is proved that: (i) ${\cal F}\leq 2$ for matter…

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astro-ph.GA

On the Jeans criterion in hydrostatic stratified media

Mahmood Roshan, Asiyeh Habibi

The classical Jeans stability criterion neglects spatial gradients in background physical quantities such as density and pressure. Here, we revisit the Jeans analysis for a non-rotating fluid in hydrostatic equilibrium, explicitly accounting for these gradients and deriving a modified dispersion relation governing perturbation propagation. Using physical arguments, we show why the Jeans swindle is not required to derive the Jeans criterion for perturbations that are small compared to the size of…

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astro-ph.IM

Breakthrough Listen's Automated Commensal Technosignature Survey with MeerKAT

Daniel J. Czech, David H. E. MacMahon, Ian Heywood, Chenoa D. Tremblay, Matt Lebofsky, Kevin Lacker, Cherry Ng, Dave Horn et al.

The search for extraterrestrial intelligence (SETI) is an ongoing effort to detect technosignatures, evidence of technologically capable life beyond Earth. Conducting a comprehensive SETI programme requires a large amount of telescope time, which must be balanced with the science goals of a given observatory. Fortunately, many modern radio telescopes offer commensal access to the data they produce, allowing multiple scientific programmes to operate in parallel. The MeerKAT radio telescope in Sou…

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astro-ph.GA

Disc Candidates in IC 2395: A WISE Survey of the Kinematically Confirmed Membership

Daniel Rose

Circumstellar disc dissipation timescales constrain the window available for planet formation. At approximately 9 Myr, IC 2395 lies at a critical epoch in primordial disc evolution, yet no kinematically selected disc census exists beyond the inner cluster core. A wide-field survey of IC 2395, extending to a 2 degree radius, establishes a kinematically selected disc census and evaluates the frequency of planet-forming environments in the outer cluster field. Using a high-purity catalogue of 173 m…

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astro-ph.IMastro-ph.EP

ANDES, the high-resolution spectrograph of the ELT: simulated performance of the CORO module and overview of the high-contrast capabilities for exoplanet observations

M. N'Diaye, A. Simonnin, A. Spang, P. Berio, A. Chiavassa, G. Agapito, C. Bailet, G. Carlà et al.

We present the simulated performance of the coronagraph (CORO) module for ANDES, the Extremely Large Telescope (ELT) high-resolution spectrograph. ANDES aims to address a broad range of science cases, including the characterization of the atmosphere of exoplanets. With a first light envisioned by 2035, the instrument baseline features a modular fiber-fed echelle spectrograph with visible and near-infrared ultra-stable spectral arms to provide a simultaneous spectral range of 0.4-1.8\,$μ$m with a…

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astro-ph.IM

Updating the SCExAO/CHARIS polarimetric calibration following the Nasmyth beam-switcher upgrade

Thomas McIntosh, Manxuan Zhang, Briley L. Lewis, Miles Lucas, Maxwell A. Millar-Blanchaer, Jaren Ashcraft, Kyohoon Ahn, Jeffrey Chilcote et al.

Subaru/SCExAO/CHARIS enables near-infrared integral field spectropolarimetry. Quantitative polarimetry is useful for a variety of science cases, particularly measurements related to dust grain properties in circumstellar disks. This capability requires correcting for polarization effects from the optical path via a Mueller matrix model. We present an updated model accounting for the recently installed SCExAO near-infrared wavefront sensor YJH50 dichroic beamsplitter and the major Subaru Nasmyth…

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astro-ph.IMphysics.app-ph

Technologies and novel components for broadband splitting and coupling in pairwise and nulling interferometry

Harry-Dean Kenchington Goldsmith, Nemanja Jovanovic, Anusha Pai Asnodkar, Sanny Ahmed, Elsa Huby, Sylvestre Lacour, Michael Fitzgerald, Yoo Jung Kim et al.

Passive and active photonic components are central to the continued development of astronomical photonic integrated circuits (PICs), although achieving broadband achromatic performance remains a significant challenge. This work presents broadband evanescent tri-couplers, tapered directional couplers, and a chromatically controlled achromatic intensity modulator for astronomical interferometry in the J- and H-bands. Silicon nitride and silicon oxide provide complementary low-loss platforms, while…

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astro-ph.COastro-ph.GA

Interpreting the stacked kinetic SZ effect I: velocity reconstruction and non-linear velocity effects

Lurdes Ondaro-Mallea, Raul E. Angulo, Boryana Hadzhiyska, Joop Schaye

The stacked kinetic Sunyaev-Zel'dovich (kSZ) signal probes the velocity-weighted projected gas momentum around galaxies, and is emerging as a powerful probe of gas fractions and baryonic feedback. Its interpretation, however, rests on several assumptions that we test in this pair of companion papers. Using the FLAMINGO hydrodynamical simulations and DESI-like galaxy mocks for luminous red galaxies (LRGs), the bright galaxy sample (BGS), and emission-line galaxies (ELGs), we identify the ingredie…

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gr-qcastro-ph.HE

Dark matter imprints on a caustic encounter in an effective spinning black hole binary lens

Mohsen Fathi

We ask whether a cored dark matter (DM) correction can leave a resolved caustic trace after a spinning vacuum binary is allowed to imitate it. The vacuum comparison varies lens scale, common spin, separation, mass ratio, projected spin angle, and one phase offset fitted over the full orbit. Nearby unequal component spins and projected directions are also tested. The best high-resolution fit remains the equal-mass, common-spin model. In the selected encounter, the local root mean square residual…

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astro-ph.GA

The ALMA-QUARKS Survey: Properties of Hot Molecular Fragments in the Massive Protocluster IRAS 17233-3606

Li Chen, Sheng-Li Qin, Dongting Yang, Wenyu Jiao, Tie Liu, Paul F. Goldsmith, Zhenying Zhang, Chuanshou Li et al.

To investigate the physical mechanisms of fragmentation within the hot molecular core of the massive protocluster IRAS 17233-3606 (G351.78-0.54), we carried out a detailed analysis of continuum and lines, using the ALMA Band 3 data from the ATOMS survey and Band 6 data from the QUARKS survey. The low-resolution 3 mm data reveal a massive hot core MM1 with a mass of ~81.3 Msun, and a prominent ultracompact (UC) HII region MM2, while the high-resolution data resolve MM1 into 11 hot molecular fragm…

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astro-ph.GA

X-ray disc reverberation modelling of the X-ray/UV/optical spectral/timing properties of Fairall 9

M. Polioudakis, M. Papoutsis, I. E. Papadakis, C. panagiotou, E. Kammoun, M. Dovciak

Multiwavelength monitoring surveys of active galactic nuclei (AGN) have revealed correlated variability observed in the X-ray, UV, and optical bands. X-ray reverberation, arising from the absorption of X-rays illuminating the accretion disc, provides a self-consistent physical framework for interpreting these observations and imposing constraints on the geometry and energetics of accretion flows and X-ray coronae. We aim to apply the X-ray disc reverberation framework to the Seyfert 1 galaxy Fai…

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hep-phastro-ph.HE

Testing selectively enhanced QCD axions couplings as an explanation of the RX J1856.5-3754 hard X-ray excess

Charul Rathod, Madhukar Mishra, P. K Das

We explore the possibility of explaining hard X-ray data obtained from one of the Magnificent Seven (M7) neutron-stars (NSs) employing QCD axion-converted photons. The emission of thermal axions along with neutrinos from the core has been considered. We adopt the nucleon-nucleon bremsstrahlung process as the baseline axion production mechanism and Cooper-pair breaking and formation (PBF) as an additional process. We investigate here whether the selectively enhanced QCD axion coupling model can b…

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astro-ph.GA

Correlation between the two-armed $V_R$ spiral in the $Z$--$V_Z$ plane and moving groups

Yan Xu, Chao Liu, Chengdong Li, Heidi Neiberg, Hao Tian, Hua Jian Wang, Xiao Dian Chen, Li Cai Deng et al.

We use a cross-matched sample of 3.7 million stars from Gaia DR3 and LAMOST DR7 to investigate the velocity substructures in the Milky Way disk. The median radial velocity $V_R$ as a function of guiding-center radius $R_g$ exhibits alternating positive and negative stripes, which are strongly correlated with known moving groups. By examining the $V_R$ distribution in the $Z$--$V_Z$ phase space, we find that the D1, P2, D2, and P3 $V_R$ stripes display clear two-armed spirals. Among the moving gr…

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